1. Field of the Invention
The present invention relates to a composite electronic part, and more particularly, it relates to a composite electronic part which comprises a capacitor element and a film resistor formed on its outer surface.
2. Description of the Background Art
A composite electronic part, which is capable of providing at least a capacitance component and a resistance component, can be manufactured in the following manner, for example: First, a multilayer ceramic capacitor element is prepared. The outer surface of this capacitor element is made of a dielectric ceramic material such as barium titanate, for example, and a plurality of internal electrodes are formed in the interior of such a dielectric ceramic member, to be capable of providing capacitance. A plurality of external terminals are formed on the outer surface of the capacitor element, in order to correct the capacitance to external circuits. Further, a plurality of wiring patterns are formed on the outer surface of the capacitor element, to be connected with the plurality of external terminals respectively. In addition, a film resistor is formed on the outer surface of the capacitor element, i.e., the dielectric ceramic member, in order to connect at least two of the wiring patterns with each other.
Such a film resistor is generally trimmed with a laser beam after formation thereof, in order to provide a prescribed resistance value.
However, although it is easy to partially trim the film resistor with a laser beam, it may unexpectedly be difficult to bring its resistance value to a prescribed level.
As the result of a study of the cause of such difficulty, it has been recognized that not only the film resistor but also the surface of the dielectric ceramic member, forming the capacitor element, is trimmed by the laser beam in the conventional trimming method. Thus, it can be inferred that the resistance of the dielectric ceramic member is reduced due to a change of its crystal structure since the dielectric ceramic member is at least rapidly heated by the laser beam when its surface is trimmed with the laser beam, and thereafter quenched to room temperature.
In order to prevent such a problem, the laser output may simply be suppressed so that the surface of the dielectric ceramic member is not influenced by the laser beam. In this case, however, it is impossible to sufficiently trim the film resistor.